CamSpec uses analytic approximations to the covariance matrices of
the pseudo-spectra derived under the assumptions of narrow window
functions and uncorrelated, but anisotropic, pixel noise
(\((\sigma ^T_i)^2\) , \((\sigma ^Q_i)^2\) , \((\sigma ^U_i)^2\) )
[1]}, [2]}, [3]}, [4]}. The components of the covariance matrix \({\bf M}\) 
are given in Sect. REF . Idealised
simulations [1]}, [3]} show that these
expressions are accurate to typically percent level precision at high
multipoles for typical Galactic sky masks for TT, TE and EE spectra,
but are only accurate at the \(\sim 10 \%\)  level for spectra involving
B-modes.
